Eventlet Example ServerΒΆ
This example is a basic HTTP/2 server written using the eventlet concurrent networking framework. This example is notable for demonstrating how to configure PyOpenSSL, which eventlet uses for its TLS layer.
In terms of HTTP/2 functionality, this example is very simple: it returns the request headers as a JSON document to the caller. It does not obey HTTP/2 flow control, which is a flaw, but it is otherwise functional.
1# -*- coding: utf-8 -*-
2"""
3eventlet-server.py
4~~~~~~~~~~~~~~~~~~
5
6A fully-functional HTTP/2 server written for Eventlet.
7"""
8import collections
9import json
10
11import eventlet
12
13from eventlet.green.OpenSSL import SSL, crypto
14from h2.config import H2Configuration
15from h2.connection import H2Connection
16from h2.events import RequestReceived, DataReceived
17
18
19class ConnectionManager(object):
20 """
21 An object that manages a single HTTP/2 connection.
22 """
23 def __init__(self, sock):
24 config = H2Configuration(client_side=False)
25 self.sock = sock
26 self.conn = H2Connection(config=config)
27
28 def run_forever(self):
29 self.conn.initiate_connection()
30 self.sock.sendall(self.conn.data_to_send())
31
32 while True:
33 data = self.sock.recv(65535)
34 if not data:
35 break
36
37 events = self.conn.receive_data(data)
38
39 for event in events:
40 if isinstance(event, RequestReceived):
41 self.request_received(event.headers, event.stream_id)
42 elif isinstance(event, DataReceived):
43 self.conn.reset_stream(event.stream_id)
44
45 self.sock.sendall(self.conn.data_to_send())
46
47 def request_received(self, headers, stream_id):
48 headers = collections.OrderedDict(headers)
49 data = json.dumps({'headers': headers}, indent=4).encode('utf-8')
50
51 response_headers = (
52 (':status', '200'),
53 ('content-type', 'application/json'),
54 ('content-length', str(len(data))),
55 ('server', 'eventlet-h2'),
56 )
57 self.conn.send_headers(stream_id, response_headers)
58 self.conn.send_data(stream_id, data, end_stream=True)
59
60
61def alpn_callback(conn, protos):
62 if b'h2' in protos:
63 return b'h2'
64
65 raise RuntimeError("No acceptable protocol offered!")
66
67
68def npn_advertise_cb(conn):
69 return [b'h2']
70
71
72# Let's set up SSL. This is a lot of work in PyOpenSSL.
73options = (
74 SSL.OP_NO_COMPRESSION |
75 SSL.OP_NO_SSLv2 |
76 SSL.OP_NO_SSLv3 |
77 SSL.OP_NO_TLSv1 |
78 SSL.OP_NO_TLSv1_1
79)
80context = SSL.Context(SSL.SSLv23_METHOD)
81context.set_options(options)
82context.set_verify(SSL.VERIFY_NONE, lambda *args: True)
83context.use_privatekey_file('server.key')
84context.use_certificate_file('server.crt')
85context.set_npn_advertise_callback(npn_advertise_cb)
86context.set_alpn_select_callback(alpn_callback)
87context.set_cipher_list(
88 "ECDHE+AESGCM"
89)
90context.set_tmp_ecdh(crypto.get_elliptic_curve(u'prime256v1'))
91
92server = eventlet.listen(('0.0.0.0', 443))
93server = SSL.Connection(context, server)
94pool = eventlet.GreenPool()
95
96while True:
97 try:
98 new_sock, _ = server.accept()
99 manager = ConnectionManager(new_sock)
100 pool.spawn_n(manager.run_forever)
101 except (SystemExit, KeyboardInterrupt):
102 break